Prevalence and Co-Occurring Conditions

Rashmi Nemade, Ph.D., edited by Kathryn Patricelli, MA

Although major depressive disorder (MDD) can appear at any age, it typically is first seen during puberty. The highest rate of MDD is seen with people in their 20's but can easily occur later in life. In any 12-month period, about 7% of the population has MDD. There are differences by age group that are seen. For example, the people who are 18-29-years old are 3 times more likely to have major depressive disorder than people who are 60 or older. Women experience MDD at a rate that is 1.5-3 times higher than men beginning in early adolescence.

People with major depressive disorder often have substance-related disorders, panic disorder, obsessive-compulsive disorder, eating disorders, and borderline personality disorder.

Formal DSM Diagnoses for Other Depressive Disorders

As mentioned in the introduction to this center, we are primarily focusing this discussion on Major Depressive Disorder. However, we also want to take some time to briefly discuss some other disorders that can share symptoms with Major Depressive Disorder. These include:

As you can tell by the length of the above list of conditions, determining which of these best describes a person's particular collection of depression symptoms can be tricky. At times, clinicians must "play detective" as they try to piece together an explanation for why someone feels depressed. You may wonder why a mental health professional spends so much time and effort coming up with a specific label. After all, people who have depressive symptoms feel bad, and have some level of trouble that impacts their ability to function in their daily lives.

A correct diagnostic label can help a therapist narrow down the treatment options, and then get the person on the road to recovery more quickly. A medical example may be helpful here. There is a wide variety of reasons that someone can develop a fever. This could include having a cold, strep throat, cancer, or rheumatoid arthritis. The doctor must spend some time determining the exact cause of the symptoms in order to prescribe the appropriate treatment. Obviously, the treatments for a cold and cancer are very different, so pinpointing the diagnosis is important. Similarly, there are a long list of reasons why someone develops depressive symptoms. Finding out the cause (and the best treatment) is no less important when it comes to treating a depressive disorder. We'll talk about the strategies used to come up with the best diagnosis in a later section of this center.